BlueCat strongly recommends deploying DNS Edge service points behind a load balancer if that's viable in your network infrastructure. Load balancers should be configured to handle traffic for both UDP and TCP protocols. The load balancer must be configured to pass the original client/source IP address to the service point farm.
The most common method of doing this for large scale deployments is to use the direct server return (DSR) load balancing method , also known as MAC-based forwarding. In this method, the load balancer distributes traffic to the service point farm at layer 2 rather than layer 3 or higher. This is so the client's IP address can be passed through unmodified. This also requires that each service point be configured with the load balancer's public VIP on a loopback interface so all the service points can respond to queries using the VIP instead of their own IP address.
Configuring commercial load balancers is beyond the scope of this guide. This section describes DSR, gives a comparison of proxy and DSR load balancing methods, and explains how to configure the VIP on a service point.
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